CN212256121U

CN212256121U - Temperature control protection device for PTC and NTC heating wire

Info

Publication number: CN212256121U
Application number: CN202021376609.6U
Authority: CN
Inventors: 汪振中
Original assignee: Shanghai Wangshan Industrial Co ltd
Current assignee: Shanghai Wangshan Industrial Co ltd
Priority date: 2020-04-02
Filing date: 2020-07-14
Publication date: 2020-12-29
Anticipated expiration: 2030-07-14
Also published as: CN111796614A

Abstract

The utility model discloses a temperature control protection device for PTC and NTC heating wire, which comprises a device shell and a control circuit arranged in the device shell, wherein the control circuit consists of an AC input module, a protection module, an EMC module, a DC voltage stabilizing module, a synchronization module, an MCU control module, an LED display module, a key operation module, a voltage detection module, a current detection module, an NTC detection module, a trigger module, a heating module and a temperature detection module; the utility model has the advantages that: 1. the risk that the blanket body is too high in temperature and the heating wire is melted after the silicon controlled rectifier is broken down is effectively avoided. 2. The ambient temperature detection circuit and the blanket body over-temperature detection circuit are combined together. The PTC temperature control circuit can be used for calibrating the control parameters of the PTC according to the environmental temperature when leaving a factory, and can also be used for controlling the heating silicon controlled rectifier to be turned off according to the temperature of the blanket body leakage protection resistor so as to prevent the temperature fuse from being blown by mistake. The temperature control precision and stability of the product are enhanced.

Description

Temperature control protection device for PTC and NTC heating wire

Technical Field

The utility model relates to a temperature control technical field specifically is a temperature control protection device that is used for PTC and NTC heating wire.

Background

PTC material is a semiconductor resistor having a positive temperature coefficient, and its resistance value increases significantly with an increase in temperature when the curie temperature is exceeded.

NTC material is a semiconductor resistor with a negative temperature coefficient, the resistance value of which decreases significantly with increasing temperature above the curie temperature.

The PTC/NTC heating wire is characterized in that a layer of detection wire and a layer of PTC heating wire are arranged in a PVC insulating layer shell, and a layer of NTC insulating material is filled between the detection wire and the PTC heating wire. The heating elements in the existing heating blankets, electric blankets, pet pads, heating boots, massage heating pads, human body local heating products, warm-up pads, dinner plate heating pads and other articles heat-preservation and heating series products often adopt PTC/NTC heating wires.

However, at present, in the traditional electric heating products such as heating pads, electric blankets and the like at home and abroad, a common heating wire is adopted for heating, a temperature controller is adopted for controlling the temperature, the temperature control precision error is large, the recovery time is long, the temperature stability is poor, the heating effect is obvious in different use environments, a user feels insufficient heat when the environmental temperature is low, the comfort level is poor, and the products do not have any safety protection function when being abnormally used. The temperature control product adopting a pure PTC heating wire or pure PTC temperature measurement cannot protect local or single-point over-temperature and overheating of the product in the aspect of safety, potential safety hazards exist in abnormal use, and the product is possibly damaged when being out of work. And another kind of electric heating products, although adopting PTC/NTC heating wire, have the function of protecting the local or single-point overheat of the product by using NTC characteristic, determine whether to close the controlled silicon by judging whether the voltage drop generated on the sampling resistor R30 by the NTC insulating material due to the larger leakage current formed by the local high temperature reaches the set value of the main control chip IC1, thus realizing the protection purpose. However, if the thyristor breaks down, the protection purpose can be realized only by waiting until the temperature is higher than the fusing heating wire and utilizing the large leakage current to cause the resistor to generate heat to fuse the temperature fuse. The disadvantages are obvious.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a temperature control protection device for PTC and NTC heating wire to solve the problem that proposes among the above-mentioned background art.

In order to achieve the above object, the utility model provides a following technical scheme:

a temperature control protection device for PTC and NTC heating wires comprises a device shell and a control circuit arranged in the device shell, wherein the control circuit consists of an alternating current input module, a protection module, an EMC module, a direct current voltage stabilizing module, a synchronization module, an MCU control module, an LED display module, a key operation module, a voltage detection module, a current detection module, an NTC detection module, a trigger module, a heating module and a temperature detection module, the alternating current input module is connected with the EMC module through the protection module, the protection module comprises a short circuit protection module and an electric leakage protection module, the EMC module respectively supplies power to other power utilization modules, the MCU control module is respectively connected with the direct current voltage stabilizing module, the synchronization module, the LED display module, the key operation module, the voltage detection module, the current detection module, the NTC detection module, the trigger module and the temperature detection module, the trigger module is also connected with the, the heating module is also respectively connected with the current detection module and the NTC detection module, the earth leakage protection module comprises a temperature fuse TF1, a resistor R7, a rectifier diode D1, a resistor R23 and a rectifier diode D4, one end of the resistor R7 is connected with a current fuse F1, the other end of the resistor R7 is connected with the cathode of the rectifier diode D1, the cathode of the rectifier diode D4 is connected with a temperature fuse TF1, one end of the resistor R23 is connected with the anode of the rectifier diode D1, the other end of the resistor R23 is connected with a detection line, the temperature fuse TF1 is positioned between the resistor R7 and the resistor R23 on the PCB, a sampling thermistor in the temperature detection module is tightly attached to the temperature fuse TF1, the resistor R7 or the resistor R23 on the PCB, the heating module is composed of a PTC heating wire in a PTC/NTC heating wire and a contactless detection wire and a low-current controllable bidirectional thyristor TR2 in series, the PTC heating wire comprises a, one end of the PTC heating wire is connected with a live wire of alternating current commercial power through a fuse F1, the other end of the PTC heating wire is connected with a main electrode of a bidirectional controllable silicon TR2, the main electrode of the bidirectional controllable silicon TR2 is connected with one end of a sampling resistor R30 in the current detection module, the other end of the sampling resistor R30 is connected with a temperature fuse TF1, a gate electrode of the bidirectional controllable silicon TR2 is connected with one end of a current limiting resistor R27 in the trigger circuit, the leakage protection module further comprises the bidirectional controllable silicon TR1, a trigger resistor R6 and an anti-interference resistor R19, an electrode T2 of the bidirectional controllable silicon TR1 is connected with one end of a resistor R7, a cathode of a rectifier diode D1 and an electrode T1 of the TR1 is connected with the temperature fuse TF1, one end of the trigger resistor R6 is connected with a 14 th pin of the main control chip, the other end of the trigger resistor R6 is connected with the gate electrode of.

As a further technical solution of the present invention: the alternating current input module is a power line with a plug, the plug end is directly inserted into an alternating current commercial power socket, and the other end is welded on the welding discs of a live wire end L and a zero line end N of the printed circuit board.

As a further technical solution of the present invention: NTC and broken string detection module are resistance series connection bleeder circuit, contain the NTC insulating layer of PTC/NTC heating wire, the detection line, divider resistance R21, divider resistance R22, divider resistance R21 and divider resistance R22 are established ties mutually and are connect temperature fuse TF1, zero line end N, 15 feet and divider resistance R22's one end of main control chip IC1 are connected to divider resistance R21's the other end, GND is connected to divider resistance R22's the other end.

As a further technical solution of the present invention: the main control chip module comprises a main control chip IC1, and a 16 th pin of the main control chip IC1 is connected with GND; the 1 st pin is connected with VCC; 2-6 are configured as LED display drivers; the 15 th pin is configured as an analog input port and is connected with the NTC and the disconnection detection signal; the 10 th pin is configured as an analog input port and is connected with a current detection signal; the 13 th pin is configured as a simulation input port and connected with an operation key; the 9 th pin is configured as a push-pull output port and is connected with a trigger circuit of a controllable silicon TR 2; the 14 th pin is configured as a push-pull output port and is connected with a trigger circuit of the protection controllable silicon TR 1; the 8 th pin is configured as an analog input port and receives the voltage detection signal; the 7 th pin is configured as an input port and is connected with a synchronous signal; pin 12 is configured as an analog input port to receive the temperature sensing signal.

As a further technical solution of the present invention: the display module is composed of an LED display circuit, the operation module is 4 light touch keys, the light touch keys are connected in series for voltage division and then connected with the 13 th pin of the main control chip IC1, and the other end of the light touch key is connected with GND.

As a further technical solution of the present invention: the EMC module comprises a voltage dependent resistor VR1, a parallel branch formed by an X capacitor C1 and a first resistor R9, one end of the parallel branch is connected with the output end of a current fuse F1, and the other end of the parallel branch is connected with the other end of a temperature fuse TF1 of the alternating current input module.

As a further technical solution of the present invention: the direct-current voltage stabilizing module comprises a resistor R2, one end of the resistor R2 is connected with one end of the EMC module, the other end of the resistor R2 is connected with one end of a voltage reducing capacitor C2, the other end of the voltage reducing capacitor C2 is connected with the anode of a rectifier diode D3 and the cathode of a rectifier diode D2, the anode of a rectifier diode D2 is connected with the other end of the temperature fuse, the cathode of the rectifier diode D3 is connected with the cathode of a voltage stabilizing diode ZD2, the anode of an electrolytic capacitor C8, one end of a ceramic chip capacitor C9 and one end of a resistor R24, the anode of a voltage stabilizing diode ZD2, the cathode of an electrolytic capacitor C8, the other end of a ceramic chip capacitor C9 and the other end.

As a further technical solution of the present invention: the synchronous module is composed of a sampling and shaping circuit, the sampling circuit comprises a resistor R5 and a cathode of a voltage regulator tube ZD1, a clamping diode is arranged in the main control chip, one end of a resistor R5 in the synchronous module is connected with the output end of a current fuse F1, the other end of the resistor R5 is connected with the cathode of the voltage regulator tube ZD1 and a pin 7 of the main control chip IC1, and the anode of the voltage regulator tube ZD1 is connected with the GND end of the direct current voltage regulator module.

As a further technical solution of the present invention: the trigger module transmits trigger pulses to the bidirectional controllable silicon in a resistance current-limiting and capacitance coupling mode, one end of a first coupling capacitor C11 is connected with the 9 th pin of a main control chip IC1, the other end of the first coupling capacitor C11 is connected with one end of a current-limiting resistor R27, the other end of the current-limiting resistor R27 is connected with the gate of the bidirectional controllable silicon TR2, and an anti-interference resistor R26 is bridged between the gate and the main electrode of the bidirectional controllable silicon TR 2.

As a further technical solution of the present invention: the current detection module is including sampling resistor R30 and isolation resistor R25, and the main electrode of bidirectional triode thyristor TR2 in the heating module is connected to the one end of sampling resistor R30 and the one end of isolation resistor R25, and temperature fuse TF1 is connected to the sampling resistor R30 other end, and the 10 th foot of main control chip IC1 is connected to the other end of isolation resistor R25, the temperature detection module is including sampling thermistor NTC1 and divider resistor R20, filter capacitor C7, and the one end of sampling thermistor NTC1 connects VCC, the other end connects the one end of divider resistor R20, and the other end of divider resistor R20 connects GND, and filter capacitor C7 and R20 are parallelly connected. The other end of the sampling thermistor NTC1 and one end of the divider resistor R20 are connected with the 12 th pin of the main control chip IC 1.

Compared with the prior art, the beneficial effects of the utility model are that: 1. the risk that the blanket body is too high in temperature and the heating wire is melted after the silicon controlled rectifier is broken down is effectively avoided. 2. The heating is controlled by a single controllable silicon, and the temperature rise of the control panel is low. 3. The active protection circuit is skillfully combined with the leakage protection circuit, so that elements are simplified, and the implementation on a control board is facilitated. And after the controllable silicon TR1 of the active protection circuit is switched on, R7 is connected to a mains supply alternating current loop, so that TF1 can be fused by heating more quickly, and the protection is faster. 4. The ambient temperature detection circuit and the blanket body over-temperature detection circuit are combined together. The PTC temperature control circuit can be used for calibrating the control parameters of the PTC according to the environmental temperature when leaving a factory, and can also be used for controlling the heating silicon controlled rectifier to be turned off according to the temperature of the blanket body leakage protection resistor so as to prevent the temperature fuse from being blown by mistake. The temperature control precision and stability of the product are enhanced.

Drawings

Fig. 1 is a block diagram of the circuit of the present invention.

Fig. 2 is a schematic circuit diagram.

FIG. 3 is a diagram of synchronization and trigger waveforms.

Fig. 4 is a schematic diagram of NTC and disconnection detection.

Fig. 5 is a schematic diagram of leakage protection.

Fig. 6 is a schematic diagram of the breakdown protection of the main thyristor.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

Referring to fig. 1-6, example 1: a temperature control protection device for PTC and NTC heating wires comprises a device shell and a control circuit arranged in the device shell, wherein the control circuit consists of an alternating current input module, a protection module, an EMC module, a direct current voltage stabilizing module, a synchronization module, an MCU control module, an LED display module, a key operation module, a voltage detection module, a current detection module, an NTC detection module, a trigger module, a heating module and a temperature detection module, the alternating current input module is connected with the EMC module through the protection module, the protection module comprises a short circuit protection module and an electric leakage protection module, the EMC module respectively supplies power to other power utilization modules, the MCU control module is respectively connected with the direct current voltage stabilizing module, the synchronization module, the LED display module, the key operation module, the voltage detection module, the current detection module, the NTC detection module, the trigger module and the temperature detection module, the trigger module is also connected with the, the heating module is also respectively connected with the current detection module and the NTC detection module, the earth leakage protection module comprises a temperature fuse TF1, a resistor R7, a rectifier diode D1, a resistor R23 and a rectifier diode D4, one end of the resistor R7 is connected with a current fuse F1, the other end of the resistor R7 is connected with the cathode of the rectifier diode D1, the cathode of the rectifier diode D4 is connected with a temperature fuse TF1, one end of the resistor R23 is connected with the anode of the rectifier diode D1, the other end of the resistor R23 is connected with a detection line, the temperature fuse TF1 is positioned between the resistor R7 and the resistor R23 on the PCB, a sampling thermistor in the temperature detection module is tightly attached to the temperature fuse TF1, the resistor R7 or the resistor R23 on the PCB, the heating module is composed of a PTC heating wire in a PTC/NTC heating wire and a contactless detection wire and a low-current controllable bidirectional thyristor TR2 in series, the PTC heating wire comprises a, one end of the PTC heating wire is connected with a live wire of alternating current commercial power through a fuse F1, the other end of the PTC heating wire is connected with a main electrode of a bidirectional controllable silicon TR2, the main electrode of the bidirectional controllable silicon TR2 is connected with one end of a sampling resistor R30 in the current detection module, the other end of the sampling resistor R30 is connected with a temperature fuse TF1, a gate electrode of the bidirectional controllable silicon TR2 is connected with one end of a current limiting resistor R27 in the trigger circuit, the leakage protection module further comprises the bidirectional controllable silicon TR1, a trigger resistor R6 and an anti-interference resistor R19, an electrode T2 of the bidirectional controllable silicon TR1 is connected with one end of a resistor R7, a cathode of a rectifier diode D1 and an electrode T1 of the TR1 is connected with the temperature fuse TF1, one end of the trigger resistor R6 is connected with a 14 th pin of the main control chip, the other end of the trigger resistor R6 is connected with the gate electrode of.

The alternating current input module is a power line with a plug, the plug end is directly inserted into an alternating current commercial power socket, the other end is welded on the welding discs of a live wire end L and a zero line end N of the printed circuit board, and the alternating current input module is used for supplying power to the temperature control and protection device.

The short-circuit protection module consists of a current fuse F1, one end of the current fuse F1 is connected to the live line terminal L, and the output end of the current fuse F1 is connected to one end of the EMC module. The short-circuit protection module has the function of being quickly fused when abnormal large current occurs in a circuit of the temperature control and protection device, so that high temperature and even fire or explosion accidents are prevented, and the safety of products is ensured.

The alternating current power supply required by the temperature control and protection device is introduced through a power line of the alternating current input module, and is subjected to treatment such as improvement of anti-interference capability of the device, reduction of disturbance degree of the device, suppression of surge voltage of the alternating current power supply and the like by the EMC module after passing through a fuse F1 connected to a live wire end L, so that the quality of the alternating current power supply is pure, and the pure alternating current power supply is supplied to the direct current voltage stabilizing module, the synchronization module 5, the main control chip module, the voltage detection module, the NTC and disconnection detection module, the temperature detection module and the heating module for use.

The EMC module is formed by connecting a piezoresistor VR1, an X capacitor C1 and a resistor R9 in parallel, one end of the EMC module is connected to the other end of the current fuse F1 after the EMC module is connected in parallel, and the other end of the EMC module is connected to the other end of the temperature fuse after the EMC module is connected in parallel. The X capacitor C1 and the resistor R9 have the functions of improving the anti-interference capability of the device to meet the requirement of safety certification and reducing the disturbance degree of the device to a power grid to meet the requirement of safety certification, and the voltage dependent resistor VR1 has the function of inhibiting the impact of surge voltage of an alternating current power supply on the temperature control and protection device of the PTC/NTC heating wire.

The direct current voltage stabilizing module is a circuit structure of resistance-capacitance voltage reduction, rectification, voltage stabilization and filtering, and is used for converting alternating current commercial power into a stable 5V direct current power supply and supplying power to low-voltage circuits such as the synchronization module, the main control chip module, the display module and the like. One end of a resistor R2 is connected with one end of the EMC module, the other end of the resistor R2 is connected with one end of a buck capacitor C2, the other end of the buck capacitor C2 is connected with the anode of a rectifier diode D3 and the cathode of a rectifier diode D2, the anode of a rectifier diode D2 is connected with the other end of the temperature fuse, the cathode of a rectifier diode D3 is connected with the cathode of a voltage regulator diode ZD2, the anode of an electrolytic capacitor C9, one end of a ceramic chip capacitor C9, one end of a resistor R24, the anode of a voltage regulator diode ZD2, the cathode of an electrolytic capacitor C8, the other end of a ceramic chip capacitor C9 and the other end of a resistor R. During the negative half cycle of the alternating current power supply, the electric energy returns to a fire wire end L through a temperature fuse TF1, a rectifier diode D2, a voltage reduction capacitor C2, a resistor R2 and a fuse F1, and the stored electric energy of the voltage reduction capacitor C2 during the positive half cycle is discharged. During the positive half cycle of the alternating current power supply, electric energy returns to a zero line end N through a live wire end L, a current fuse F1, a resistor R2, a voltage reduction capacitor C2, a rectifier diode D3, a voltage stabilizing diode ZD2, an electrolytic capacitor C8, a ceramic capacitor C9, a resistor R24 and a temperature fuse TF1, when the voltage reduction capacitor C2 is charged, a stable 5V direct current power supply is obtained at two ends of the voltage stabilizing diode ZD2, the electrolytic capacitor C8, the ceramic capacitor C9 and the resistor R24 which are connected in parallel, the polarity is GND at one end connected with the temperature fuse, and VCC is at one end connected with the positive electrode of the electrolytic capacitor C8.

The synchronous module is composed of a sampling and shaping circuit, the sampling circuit comprises a resistor R5 and a voltage stabilizing diode ZD1, and a clamping diode in the main control chip is used for converting sine wave voltage of an alternating current power supply into a synchronous signal which has the same phase and the maximum voltage amplitude VCC +0.3V and is used by the main control chip IC 1. One end of a resistor R5 in the synchronous module is connected with the output end of a current fuse F1, the other end of the resistor R5 is connected with the cathode of a voltage stabilizing diode ZD1 and the 7 pins of a main control chip IC1, and the cathode of the voltage stabilizing diode is connected with the GND end of the direct current voltage stabilizing module. In the positive half cycle, the sine wave voltage of the ac power source is always high level through the live line terminal L, the current fuse F1, and the resistor R5 to the 7 th pin of the main control chip IC 1. During the negative half cycle, the sine wave voltage of the ac power supply is always at low level through the neutral terminal N, the temperature fuse TF1, the internal clamping diode of the IC1, the resistor R5, the fuse F1, and the live line terminal L, and the 7 th pin of the main control chip IC1, as shown in fig. 4.

The main control chip module is the core of the temperature control and protection device of the PTC/NTC heating wire, and the main control chip IC1 is a high cost performance microcontroller which is provided with an SOP16 package, 4K 16BitsFLASHROM, 12K 12BitsADC, 8M/4M internal vibration, 3 internal +2 external interrupt sources, 8-level stack and a built-in WDT timer. The pin configuration of the master chip IC1 is as follows: the 16 th pin is connected with GND; the 1 st pin is connected with VCC; 2-6 are configured as LED display drivers; the 15 th pin is configured as an analog input port and is connected with the NTC and the disconnection detection signal; the 10 th pin is configured as an analog input port and is connected with a current detection signal; the 13 th pin is configured as a simulation input port and connected with an operation key; the 9 th pin is configured as a push-pull output port and is connected with a trigger circuit of a controllable silicon TR 1; the 14 th pin is configured as a push-pull output port and is connected with a trigger circuit of the protection controllable silicon TR 2; the 8 th pin is configured as an analog input port and receives the voltage detection signal; the 7 th pin is configured as an input port and is connected with a synchronous signal; pin 12 is configured as an analog input port to receive the temperature sensing signal.

The display module is composed of an LED display circuit. The LED displays gear position value, timing time and fault display.

The operation module is 4 touch keys, is connected with the 13 th pin of the main control chip IC1 after series voltage division, and the other end is connected with GND. The function is to convert the key operation of pressing and releasing into different voltage signals respectively corresponding to the pins 13 of the main control chip IC1 for the detection of the main control chip IC 1. The working state of the temperature control and protection device can be set only by the touch key, and the standby state, the timing time and the working states of 1-6 grades of the device can be set according to the operation of different touch keys.

The voltage detection module is a voltage division circuit formed by serially connecting a voltage division resistor R4 and a voltage division resistor R3, one end of the voltage division resistor R4 is connected with the output end of a current fuse F1, the other end of the voltage division resistor R4 is connected with one end of a voltage division resistor R5 and the 8 th pin of a main control chip IC1, the other end of the voltage division resistor R5 is connected with GND (ground potential), the function of the voltage division circuit is to obtain an alternating current power supply from the output end of the fuse F1 to the GND end, the high-amplitude alternating current voltage is reduced to the alternating current voltage within 5V of amplitude in a linear relation and is supplied to the 8 th pin of the main control chip IC1 for analog-digital conversion.

The current detection module is a small-resistance resistor sampling circuit and comprises a sampling resistor R30 and an isolation resistor R25. One end of the sampling resistor R30 and one end of the isolation resistor R25 are connected with a main electrode of a bidirectional thyristor TR2 in the heating module, the other end of the sampling resistor R30 is connected with the temperature fuse TF1, and the other end of the isolation resistor R25 is connected with a 10 th pin of the main control chip IC 1. The current detection module is used for generating a heating current Ih in a loop of a live wire end L, a fuse F1, a PTC heating wire, the bidirectional thyristor TR2, a sampling resistor R30, a temperature fuse and a zero line end N after the bidirectional thyristor TR2 in the heating module is switched on, the heating current Ih flows through the sampling resistor R30 to obtain a corresponding voltage, the voltage is equal to the product of Ih and the resistance value of the sampling resistor R30, the voltage is supplied to a 10 th pin of a main control chip IC1 through an isolation resistor R25, analog and digital signal conversion is carried out, and a current sampling value after conversion is used as a second basis for temperature judgment.

The NTC and disconnection detection module is a resistor series voltage division circuit, and comprises a voltage division resistor R21, an NTC insulating layer of a PTC/NTC heating wire, a detection wire, and a voltage division resistor R22. The voltage dividing resistor R21 and the voltage dividing resistor R22 are connected in series and connected in parallel with the temperature fuse TF1 and the zero line end N. The other end of the divider resistor R21 is connected with the pin 15 of the main control chip IC1 and one end of the divider resistor R22, and the other end of the divider resistor R22 is connected with GND.

The NTC and disconnection detection module is used for generating disconnection detection signals and NTC detection signals, and the disconnection detection signals are acquired by an analog signal converter and a digital signal converter of the main control chip IC1 through a pin 15 of the main control chip IC 1.

In this embodiment, the operating principle of the NTC and disconnection detecting module is that the triac TR2 of the heating module is turned off In the positive half cycle of the ac power supply, and the ac power supply first generates a constant disconnection detecting current Ib In the loop of the live wire terminal L, the fuse F1, the voltage dividing resistor R21, the voltage dividing resistor R22, and the neutral wire terminal N, as shown In fig. 4, and then generates an NTC detecting current In that changes In the same direction as the temperature of the heating wire In the loop of the live wire terminal L, the fuse F1, the PTC heating wire, the NTC insulating layer, the detecting line, the voltage dividing resistor R21, the voltage dividing resistor R22, and the neutral wire terminal N unless the loop is disconnected and opened. Under the combined action of the constant wire breakage detection current Ib and the NTC detection current In which changes along with the temperature change of the heating wire, voltage drop is generated on the voltage dividing resistor R22, the voltage drops enter the analog-digital converter of the main control chip IC1 through the 15 th pin of the main control chip IC1 for conversion, and the converted data are called wire breakage and NTC sampling values and serve as judgment bases for wire breakage protection and local overheating of the heating main body. When the circuit is disconnected and opened, the voltage drop generated on the voltage-dividing resistor R22 is lower than the disconnection protection judgment reference value solidified in the program in the main control chip IC1, the main control chip IC1 turns off the bidirectional thyristor TR2 of the heating module, and meanwhile, the LED displays faults, so that the abnormal heating of a heating main body is avoided, and the product safety is ensured. When the circuit is not broken and the circuit is open and the temperature of the heating wire is low, the NTC detection current In is extremely small, only the broken wire detection current Ib generates a voltage drop on the divider resistor R22, the voltage drop is higher than the broken wire protection judgment reference value solidified In the program In the main control chip IC1 but lower than the judgment reference value solidified In the program In the main control chip IC1, the broken wire protection function and the heating body local overheating protection function do not work, and the whole device can normally work according to the set gear. When the loop is not broken and the circuit is opened and the local temperature of the heating wire is overheated, the NTC detection current In is larger, at the moment, the broken wire detection current Ib and the NTC detection current In which changes along with the temperature change of the heating wire act together, the voltage drop generated on the voltage division resistor R22 is higher than the broken wire protection judgment reference value solidified In the program In the main control chip IC1 and higher than the local overheating judgment reference value of the heating main body solidified In the program In the main control chip IC1, the broken wire protection function does not work, but the local overheating protection function of the heating main body takes effect, the main control chip IC1 turns off the bidirectional controllable silicon TR2 of the heating module, the abnormal heating of the heating main body is avoided, and the product safety is ensured.

The trigger module transmits trigger pulse to the bidirectional controllable silicon by adopting a resistance current-limiting and capacitance coupling mode, one end of a first coupling capacitor C11 is connected with the 9 th pin of a main control chip IC1, the other end of the first coupling capacitor C11 is connected with one end of a current-limiting resistor R27, the other end of the current-limiting resistor R27 is connected with the gate of the bidirectional controllable silicon TR2, and an anti-interference resistor R26 is bridged between the gate and the main electrode of the bidirectional controllable silicon TR 2. The trigger module is simple and reliable, and anti-jamming resistor can prevent the spurious triggering of bidirectional thyristor TR2 on the one hand, and in addition, even master control chip IC1 became invalid or its trigger pulse delivery outlet damaged, keep high level or low level always, all can be cut off by first coupling capacitor C11 because of the effect of keeping off direct traffic of electric capacity, and bidirectional thyristor TR2 can't reach trigger pulse current and can't switch on, avoids the main part that generates heat abnormally to generate heat, thereby ensures product safety.

The heating module is formed by connecting a PTC heating wire in a PTC/NTC heating wire and a contactless power switch element with controllable small current in series, the PTC/NTC heating wire comprises a detection wire layer, a PTC heating wire layer and an NTC insulating layer between the detection wire layer and the PTC heating wire layer, one end of the PTC heating wire is connected with a live wire of an alternating current mains supply through a fuse F1, the other end of the PTC heating wire is connected with a second main electrode of a bidirectional thyristor TR2, a first main electrode of the bidirectional thyristor TR2 is connected with one end of a sampling resistor R30 in the current detection module, the other end of the sampling resistor R30 is connected with a temperature fuse TF1, and a gate electrode of the bidirectional thyristor TR2 is connected with the other end of a current limiting resistor R27.

The heating module is used for conducting the power switch element after the alternating current power supply crosses zero and receives a trigger pulse, the two ends of the PTC heating wire obtain the alternating current power supply to generate heat, and when the trigger pulse does not exist, the power switch element is turned off, and the two ends of the PTC heating wire cannot obtain the alternating current power supply to stop heating.

The main control chip module is powered by +5V output by the direct current voltage stabilizing module, and after initialization is completed, the main program of the user program is operated circularly.

And the main control chip IC1 of the main control chip module receives the key signal of the operation module through the 13 th pin in the process of running the main program of the user program, outputs a gear indication signal according to the key instruction, and lights the corresponding LCD and backlight display.

The main control chip IC1 in the main control chip module also receives the synchronization signal of the synchronization module through the 7 th pin during the operation of the main program of the user program. Once the synchronous signal has a rising edge from '0' to '1' or a falling edge from '1' to '0', the main control chip IC1 immediately controls the on and off of the bidirectional controllable silicon TR2 in the heating module according to the current working state of the device and the detected real-time temperature, and simultaneously starts a timing subroutine of 4.167mS or 5mS corresponding to the zero crossing point to the peak point of the alternating current power supply to prepare for the next temperature detection or NTC and disconnection detection.

In the process of running a main program of a user program, once the started timing subprogram corresponding to 4.167mS or 5mS from the zero crossing point of the alternating-current power supply to the peak point is executed, the main control chip IC1 of the main control chip module immediately collects and converts the voltage signal of the voltage detection module and the current signal of the current detection module which are received by the 8 th pin and the 10 th pin, divides the voltage data by the current data after the conversion is finished, calculates the current resistance value of the corresponding PTC heating wire according to the ohm law, and corresponds to the current real-time temperature of the PTC heating wire, and the result participates in the control of the on and off of the bidirectional thyristor TR2 in the heating module.

The larger the current resistance value of the corresponding PTC heating wire is, the higher the current temperature is, and once the current resistance value is higher than the resistance value set by the gear, the main control chip IC1 turns off the bidirectional thyristor TR2 to cut off the power supply of the heating wire. After a period of time delay, the power supply of the heating wire is switched on again, the resistance value of the PTC heating wire is detected again, whether the resistance value of the PTC heating wire is reduced to the resistance value range set by the gear is judged again, and if yes, the temperature is reduced and heating is needed. If the resistance value of the PTC heating wire is still higher than the resistance value set by the gear, the power supply of the heating wire is continuously disconnected. The purpose of automatic and accurate temperature control can be achieved by circularly detecting, judging and controlling.

The main control chip IC1 of the main control chip module also receives NTC and disconnection detection signals of the NTC and disconnection detection module through the 15 th pin during the operation of the main program of the user program. Once the started timing subprogram corresponding to 4.167mS or 5mS from the zero crossing point to the peak point of the alternating current power supply is executed, acquiring, performing analog-digital conversion on the NTC and disconnection detection signals of the NTC and disconnection detection module received by the 15 pins at present, and judging whether the current state of the heating main body is a normal state or a disconnection state or a local overheating state of the heating main body according to the result of the analog-digital conversion, thereby respectively executing a normal heating or heat stopping function, a disconnection protection function and a local overheating protection function of the heating main body.

The earth leakage protection module comprises a temperature fuse, a resistor R7 and a rectifying diode D1 which are connected in series, and a resistor 23 and a rectifying diode D4 which are connected in series. One end of the resistor R7 is connected with the current fuse F1, the other end of the resistor R7 is connected with the cathode of the rectifier diode D1, the cathode of the rectifier diode D4 is connected with the anode of the temperature fuse TF1 and is connected with one end of the resistor R23, the anode of the rectifier diode D1 and the other end of the resistor R23 are connected with a detection line, and the temperature fuse TF1 is positioned between the resistor R7 and the resistor R23 on the PCB. When the blanket body leaks electricity, a large current flows through the R7 and the R23, and the R7 and the R23 generate heat and fuse the sandwiched temperature fuse TF1 to play a protection role. The leakage protection module further comprises a bidirectional thyristor TR1, a trigger resistor R6 and an anti-interference resistor R19, an electrode T2 of the bidirectional thyristor TR1 is connected with the other end of the resistor R7 and the cathode of a rectifier diode D1, an electrode T1 of the TR1 is connected with a temperature fuse TF1, one end of the trigger resistor R6 is connected with the 14 th pin of the main control chip, the other end of the trigger resistor R6 is connected with the gate of the bidirectional thyristor, and the anti-interference resistor is bridged between the gate G of the bidirectional thyristor TR1 and the electrode T1. After the current detection module detects that the heating-controlled main thyristor TR2 is broken down, the 14 th pin of the single chip microcomputer triggers and turns on the thyristor TR1, so that AC (N) forms a loop through the temperature fuse TF1, the T1-T2 pole of the thyristor TR2, the resistor R7 in the electric leakage (over-temperature) protection module, the current fuse F1 and the AC (L), and the resistor R7 rapidly heats and fuses the temperature fuse TF 1. TF1 is located in the middle of R23 and R7 on the PCB board, and the three components are closely contacted in parallel and coated with heat-conducting silicone grease. The leakage (over-temperature) protection module combines the breakdown protection of the main controllable silicon, and has the advantages of simple and reliable structure, intelligent judgment and advanced protection.

Fig. 4-6 are schematic diagrams of detection and protection of the present design, which are taken from a partial enlargement in the circuit of fig. 2, so that a part of missing contents can refer to fig. 2, and the understanding of the technical solution by those skilled in the art is not affected.

In embodiment 2, based on embodiment 1, the temperature detection module includes a sampling thermistor NTC1, a voltage dividing resistor R20, and a filter capacitor C7, one end of the sampling thermistor NTC1 is connected to VCC, the other end is connected to one end of the voltage dividing resistor R20, the other end of the voltage dividing resistor R20 is connected to GND, and the filter capacitors C7 and R20 are connected in parallel. The other end of the sampling thermistor NTC1 and one end of the divider resistor R20 are connected with the 12 th pin of the main control chip IC 1. And (4) carrying out analog and digital signal conversion, wherein the converted temperature sampling value is used as the basis for factory calibration of PTC control parameters and also used as the basis for overheating protection of the blanket body during working. Before leaving a factory, the single chip microcomputer IC1 enters a calibration mode through specific key operation, the environment temperature is calculated through the sampling voltage of a 12 th pin, the TR2 is switched on for a short time, the actual resistance value of the PTC is calculated through the sampling voltages of a 10 th pin and an 8 th pin, the actual resistance value is compared with the theoretical resistance value at the corresponding temperature, and then the correction parameter of temperature control can be obtained, so that the influence of errors of a PTC wire and an electronic element on the temperature control is reduced. The sampling thermistor NTC1 is attached to R7, R23 and a temperature fuse TF1 on a PCB, when the heating temperature of R7 and R23 rises after the carpet body is locally overheated, if the 15 th foot of the single chip microcomputer fails to timely detect the voltage conducted by the NTC, when the 15 th foot of the single chip microcomputer detects that the voltage conducted by the thermistor NTC1 is higher than a set value, the carpet body is judged to be turned off by over-temperature TR2, therefore, the TF1 is prevented from being fused, and the stability of the controller is improved.

It is obvious to a person skilled in the art that the invention is not restricted to details of the above-described exemplary embodiments, but that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. A temperature control protection device for PTC and NTC heating wires comprises a device shell and a control circuit arranged in the device shell, wherein the control circuit consists of an alternating current input module, a protection module, an EMC module, a direct current voltage stabilizing module, a synchronization module, an MCU control module, an LED display module, a key operation module, a voltage detection module, a current detection module, an NTC detection module, a trigger module, a heating module and a temperature detection module, the alternating current input module is connected with the EMC module through the protection module, the protection module comprises a short circuit protection module and an electric leakage protection module, the EMC module respectively supplies power to other power utilization modules, the MCU control module is respectively connected with the direct current voltage stabilizing module, the synchronization module, the LED display module, the key operation module, the voltage detection module, the current detection module, the NTC detection module, the trigger module and the temperature detection module, the trigger module is also connected with the, the heating module is also respectively connected with the current detection module and the NTC detection module, the earth leakage protection module comprises a temperature fuse TF1, a resistor R7, a rectifier diode D1, a resistor R23 and a rectifier diode D4, one end of the resistor R7 is connected with a current fuse F1, the other end of the resistor R7 is connected with the cathode of the rectifier diode D1, the cathode of the rectifier diode D4 is connected with a temperature fuse TF1, one end of the resistor R23 is connected with the anode of the rectifier diode D4, the other end of the resistor R23 is connected with a detection line, the temperature fuse TF1 is positioned between the resistor R7 and the resistor R23 on the PCB, a sampling thermistor in the temperature detection module is connected with the temperature fuse TF1, the resistor R7 or the resistor R23 on the PCB, and the heating module is characterized in that the heating module is formed by connecting a PTC heating wire in a PTC/NTC heating wire and a contactless small-current controllable bidirectional thyristor TR2 in series, the PTC/NTC heating, one end of the PTC heating wire is connected with a live wire of alternating current commercial power through a fuse F1, the other end of the PTC heating wire is connected with a main electrode of a bidirectional controllable silicon TR2, the main electrode of the bidirectional controllable silicon TR2 is connected with one end of a sampling resistor R30 in the current detection module, the other end of the sampling resistor R30 is connected with a temperature fuse TF1, a gate electrode of the bidirectional controllable silicon TR2 is connected with one end of a current limiting resistor R27 in the trigger circuit, the leakage protection module further comprises the bidirectional controllable silicon TR1, a trigger resistor R6 and an anti-interference resistor R19, an electrode T2 of the bidirectional controllable silicon TR1 is connected with one end of a resistor R7, a cathode of a rectifier diode D1 and an electrode T1 of the TR1 is connected with the temperature fuse TF1, one end of the trigger resistor R6 is connected with a 14 th pin of the main control chip, the other end of the trigger resistor R6 is connected with the gate electrode of.

2. The temperature control protection device for the PTC and NTC heating wire as claimed in claim 1, wherein the AC input module is a power line with a plug, the plug end is directly plugged into the AC commercial power socket, and the other end is soldered to the L and N pads of the live wire end and the neutral wire end of the printed circuit board.

3. The temperature control protection device for the PTC and NTC heating wire according to claim 2, wherein the NTC and disconnection detection module is a resistor series voltage dividing circuit comprising an NTC insulation layer of the PTC/NTC heating wire, a detection line, a voltage dividing resistor R21, a voltage dividing resistor R22, a voltage dividing resistor R21 and a voltage dividing resistor R22 connected in series and connected in parallel with the temperature fuse TF1, a zero line terminal N, the other end of the voltage dividing resistor R21 is connected with a pin 15 of the main control chip IC1 and one end of the voltage dividing resistor R22, and the other end of the voltage dividing resistor R22 is connected with GND.

4. The temperature control protection device for the PTC and NTC heating wire according to claim 3, wherein the main control chip module comprises a main control chip IC1, the 16 th pin of the main control chip IC1 is connected to GND; the 1 st pin is connected with VCC; 2-6 are configured as LED display drivers; the 15 th pin is configured as an analog input port and is connected with the NTC and the disconnection detection signal; the 10 th pin is configured as an analog input port and is connected with a current detection signal; the 13 th pin is configured as a simulation input port and connected with an operation key; the 9 th pin is configured as a push-pull output port and is connected with a trigger circuit of a controllable silicon TR 2; the 14 th pin is configured as a push-pull output port and is connected with a trigger circuit of the protection controllable silicon TR 1; the 8 th pin is configured as an analog input port and receives the voltage detection signal; the 7 th pin is configured as an input port and is connected with a synchronous signal; pin 12 is configured as an analog input port to receive the temperature sensing signal.

5. The temperature control protection device for the PTC and NTC heating wire as claimed in claim 4, wherein the display module is composed of LED display circuit, the operation module is 4 touch keys, the key is connected with the 13 th pin of the main control chip IC1 after series voltage division, and the other end is connected with GND.

6. A temperature control protection device for PTC and NTC heating wire according to claim 5, wherein the EMC module comprises a parallel branch consisting of a voltage dependent resistor VR1, an X capacitor C1 and a first resistor R9, one end of the parallel branch is connected with the output end of the current fuse F1, and the other end of the parallel branch is connected with the other end of the temperature fuse TF1 of the AC input module.

7. A temperature control protection device for PTC and NTC heating wire according to claim 6, characterized in that said DC voltage stabilizing module comprises a resistor R2, one end of the resistor R2 is connected to one end of the EMC module, the other end of the resistor R2 is connected to one end of a voltage reducing capacitor C2, the other end of the voltage reducing capacitor C2 is connected to the anode of a rectifier diode D3 and the cathode of a rectifier diode D2, the anode of the rectifier diode D2 is connected to the other end of the temperature fuse, the cathode of the rectifier diode D3 is connected to the cathode of a zener diode ZD2, the anode of an electrolytic capacitor C8, one end of a tile capacitor C9, one end of a resistor R24, the anode of a zener diode 2, the cathode of an electrolytic capacitor C8, the other end of a tile capacitor C9, and the other end of a resistor R24 is connected to the other.

8. A temperature control protection device for a PTC and NTC heating wire according to any one of claims 1-7, characterized in that the said synchronization module is composed of a sampling and shaping circuit, the sampling circuit includes a resistor R5 and the cathode of a voltage regulator tube ZD1, a main control chip internal clamping diode, one end of the resistor R5 in the synchronization module is connected with the output end of a current fuse F1, the other end of the resistor R5 is connected with the cathode of a voltage regulator tube ZD1 and the pin 7 of a main control chip IC1, and the anode of the voltage regulator tube ZD1 is connected with the GND end of a DC voltage regulator module.

9. The temperature control protection device for the PTC and NTC heating wire according to claim 8, wherein the trigger module transmits the trigger pulse to the triac by means of resistance current limiting and capacitive coupling, one end of the first coupling capacitor C11 is connected to the 9 th pin of the main control chip IC1, the other end is connected to one end of a current limiting resistor R27, the other end of the current limiting resistor R27 is connected to the gate of the triac TR2, and the anti-interference resistor R26 is connected across the gate of the triac TR2 and the main electrode.

10. The temperature control protection device according to claim 9, wherein the current detection module comprises a sampling resistor R30 and an isolation resistor R25, one end of the sampling resistor R30 and one end of the isolation resistor R25 are connected to a main electrode of a triac TR2 in the heating module, the other end of the sampling resistor R30 is connected to the temperature fuse TF1, the other end of the isolation resistor R25 is connected to the 10 th pin of the main control chip IC1, the temperature detection module comprises a sampling thermistor NTC1, a voltage dividing resistor R20 and a filter capacitor C7, one end of the sampling thermistor 1 is connected to VCC, the other end of the sampling thermistor is connected to one end of a voltage dividing resistor R20, the other end of the voltage dividing resistor R20 is connected to GND, the filter capacitors C7 and R20 are connected in parallel, and the other end of the sampling thermistor 1 and one end of the voltage dividing resistor R20 are connected to the 12 th pin of the main control chip IC 1.